<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        var arr = [1, 2, 3, 4];
        // unshiftArray(arr, 5);
        // console.log(arr); // [5, 4, 3, 2, 1]
        var newArr = arr.slice(0);
        newArr.splice(0, 1);
        console.log(newArr);
    </script>
</head>
<body>
    <button onclick="">111</button>
</body>
</html>